title: Developmental patterns of plasma insulin-like growth factor-I (IGF-I) and body growth in mice from lines divergently selected on the basis of plasma IGF-I.
abstract: A study was conducted to investigate developmental patterns of plasma concentrations of insulin-like growth factor-I (IGF-I), body growth and body composition in mice from lines selected for seven generations on the basis of low (L) or high (H) plasma IGF-I, and in a random-bred control (C) line. Litter size was standardized to eight individuals with equal sex ratios (as far as possible) within 48 h of birth. Pups were weaned at an average of 21 days and separated on the basis of sex. Blood samples were collected from one male and one female of each litter on days, 21, 42, 63 and 105 for analysis of plasma concentrations of IGF-I. The animals were then killed and analysed for water, fat and crude protein content. The plasma concentration of IGF-I was influenced by line (P less than 0.05) but not by sex. Significant (P less than 0.001) differences in liveweight between mice from L and H lines were first evident at 21 days of age. From 28 until 105 days of age the H line was significantly (P less than 0.001) heavier than both L and C lines, but differences between C and L lines were inconsistent and mostly non-significant. The growth velocity of the H line was significantly greater than that of C or L lines between 14 and 42 days of age, but differences in growth velocities of C compared with L lines were generally non-significant.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Department of Animal Science, Massey University, Palmerston North, New Zealand.
authors.forename: R A
authors.initials: RA
authors.lastname: Siddiqui
authors.forename: H T
authors.initials: HT
authors.lastname: Blair
authors.forename: S N
authors.initials: SN
authors.lastname: McCutcheon
authors.forename: D D
authors.initials: DD
authors.lastname: Mackenzie
authors.forename: P D
authors.initials: PD
authors.lastname: Gluckman
authors.forename: B H
authors.initials: BH
authors.lastname: Breier
mesh_terms: D000818:Animals; D001823:Body Composition / Q000502:physiology; D001835:Body Weight / Q000502:physiology; D005260:Female; D006128:Growth; D007334:Insulin-Like Growth Factor I / Q000378:metabolism*; D008297:Male; D051379:Mice; D008815:Mice, Inbred Strains; D013002:Somatomedins / Q000378:metabolism*
chemical_list: D013002:Somatomedins; D007334:Insulin-Like Growth Factor I